After coming from the same issue everybody else did, I am also running into the problem where only a blue screen appears. Unlike the others, I will post my full console:
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib' (no such file), '/usr/lib/lua_shared.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib' (no such file), '/usr/lib/lua_shared.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib' (no such file), '/usr/lib/lua_shared.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/lua_shared.dylib' (no such file), '/usr/lib/lua_shared.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib' (no such file), '/usr/lib/menusystem.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/menusystem.dylib' (no such file), '/usr/lib/menusystem.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib' (no such file), '/usr/lib/client.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib' (no such file), '/usr/lib/client.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib' (no such file), '/usr/lib/materialsystem.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/materialsystem.dylib' (no such file), '/usr/lib/materialsystem.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib' (no such file), '/usr/lib/resources.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/resources.dylib' (no such file), '/usr/lib/resources.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib' (no such file), '/usr/lib/gmod_audio.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/gmod_audio.dylib' (no such file), '/usr/lib/gmod_audio.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib' (no such file), '/usr/lib/client.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/client.dylib' (no such file), '/usr/lib/client.dylib' (no such file)
Attempting to load Awesomium...
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen /Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib error=dlopen(/Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib, 0x0002): tried: '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
Failed to load /Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib: (null)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen /Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib error=dlopen(/Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib, 0x0002): tried: '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
Failed to load /Volumes/Untitled/Steam/steamapps/common/GarrysMod/garrysmod/bin/html_awesomium.dylib: (null)
failed to dlopen /Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/html_awesomium.dylib error=dlopen(/Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/html_awesomium.dylib, 0x0002): tried: '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file), '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS/html_awesomium.dylib error=dlopen(GarrysMod.app/Contents/MacOS/html_awesomium.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
failed to dlopen html_awesomium.dylib error=dlopen(html_awesomium.dylib, 0x0002): tried: 'html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file), '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/html_awesomium.dylib' (no such file), '/usr/lib/html_awesomium.dylib' (no such file)
Failed to load html_awesomium.dylib: (null)
Attempting to load Stub...
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib' (no such file), '/usr/lib/html_stub.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/html_stub.dylib' (no such file), '/usr/lib/html_stub.dylib' (no such file)
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib' (no such file), '/usr/lib/GameUI.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/GameUI.dylib' (no such file), '/usr/lib/GameUI.dylib' (no such file)
failed to dlopen /Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/GameUI.dylib error=dlopen(/Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/GameUI.dylib, 0x0002): tried: '/Volumes/Untitled/Steam/steamapps/common/GarrysMod/bin/GameUI.dylib' (no such file), '/usr/lib/GameUI.dylib' (no such file)
x86-64: gmod_mcore_test=1
Parent cvar in server.dll not allowed (p2p_enabled)
Parent cvar in server.dll not allowed (props_break_max_pieces)
[MENU ERROR] Couldn't include file 'includes/init_menu.lua' - File not found (<nowhere>)
[MENU ERROR] Couldn't include file 'derma/init.lua' - File not found (<nowhere>)
[MENU ERROR] Couldn't include file 'includes/vgui_base.lua' - File not found (<nowhere>)
[MENU ERROR] Couldn't include file 'skins/default.lua' - File not found (<nowhere>)
[MENU ERROR] Couldn't include file 'includes/menu.lua' - File not found (<nowhere>)
JOY_AXIS_X: mapped to Turn (absolute)
JOY_AXIS_Y: mapped to Look (absolute)
JOY_AXIS_Z: unmapped
JOY_AXIS_R: mapped to Forward (absolute)
JOY_AXIS_U: mapped to Side (absolute)
JOY_AXIS_V: unmapped
Advanced Joystick settings initialized
Not playing a local game.
failed to dlopen GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib error=dlopen(GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib, 0x0002): tried: 'GarrysMod_Signed.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib' (no such file), '/usr/lib/ServerBrowser.dylib' (no such file)
failed to dlopen GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib error=dlopen(GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib, 0x0002): tried: 'GarrysMod.app/Contents/MacOS//Volumes/Untitled/Steam/steamapps/common/GarrysMod/GarrysMod_Signed.app/Contents/MacOS/ServerBrowser.dylib' (no such file), '/usr/lib/ServerBrowser.dylib' (no such file)
Addons have changes - remounting (x2)
Extracted 'resource/fonts/bebasneue.ttf' from workshop addon
Extracted 'resource/fonts/opensans-condbold.ttf' from workshop addon
Extracted 'resource/fonts/opensans-condlight.ttf' from workshop addon
Extracted 'resource/fonts/opensans-regular.ttf' from workshop addon
Extracted 'resource/fonts/ultra.ttf' from workshop addon